In electrostatographic reproduction apparatus a latent image charge pattern is formed on a uniformly charged charge-retentive or photoconductive member having dielectric characteristics. Pigmented marking particles, henceforth referred to as toner particles, are attracted to the latent image charge pattern to develop such image on the photoconductive member. A receiver member, such as a sheet of paper, transparency or other medium, is then brought into contact with the photoconductive member, and an electric field applied to transfer the toner particle developed image to the receiver member from the photoconductive member. After transfer, the receiver member bearing the transferred image is transported away from the photoconductive member, and the image is fixed (fused) to the receiver member by heat and pressure to form a permanent reproduction thereon.
This process can be used to create photographic quality multicolor toner images when the toner particles are small, (i.e., less than about 10 micrometers), and the receivers, typically papers, are smooth. A typical method of making a multicolor toner image involves trichromatic color synthesis by subtractive color formation. In such synthesis, multiple latent electrostatic images are formed, each representing a different color, and each image is developed with a toner of a different color. Typically, the colors will correspond to each of the three subtractive primary colors (cyan, magenta and yellow) and black, if desired. After developing each color separation on a photoconductive element, it is transferred to a receiver in registration with the other color toner images. After all the color toners have been transferred to the receiver, the toners are fixed or fused to the receiver in a fusing station. It has been found that fusing of multi-color toner particle images to a receiver member requires substantially different operating parameters than fusing standard black toner particle images to a receiver member. Moreover, the respective operating parameters may in fact be in contradistinction. That is, multi-color images require a high degree of glossiness for a full, rich depth of color reproduction; on the other hand, since glossiness for black marking particle images may significantly impair legibility, a matte finish is preferred.
The fusing station of a typical multicolor electrostatographic reproduction apparatus includes a fuser member, which can be a roller, belt, or any surface having a suitable shape for fixing thermoplastic toner particles to the receiver member. The fusing step using a roller fuser member commonly includes passing the receiver member, with the toner particle image thereon, between a pair of engaged rollers that produce an area of pressure contact known as a fusing nip. In order to form the fusing nip, at least one of the rollers typically includes a compliant or conformable layer. Heat is transferred from at least one of the rollers to the toner particles in the fusing nip, causing the toner particles to partially melt and attach to the receiver member. In the case where the fuser member is a deformable heated roller, a resilient elastomeric layer is typically bonded to the core of the roller, with the roller having a smooth outer surface. Where the fuser member is in the form of a belt, e.g., a flexible endless belt that passes around the heated roller, it typically has a smooth outer surface, which may also be hardened. The toner particle developed image on the receiver member is brought into contact with the belt in the nip between the heated roller and pressure roller, causing the toner particles to partially melt and attach to the receiver member and belt. The receiver member is transported away from the heated nip on the belt and cooled to solidify the toner particle image. The receiver member is then stripped from the belt with the toner particle image having a surface finish from the belt against which it solidified.
A belt fuser may function as the integral fusing station in a reproduction apparatus or as a post printing finishing device to alter the surface finish of the toner particle image after it exits the reproduction apparatus. As a post printing finishing device, the belt fuser may be in-line with the reproduction apparatus, meaning the image bearing receiver members are transported directly from the reproduction apparatus into the finishing device, or the belt fuser may be a stand-alone unit, meaning the image bearing receiver members are manually stacked in the finishing device which has a feeder that feeds the receiver members through the belt fusing/finishing section. The function of a post printing finishing device may be to increase or decrease the gloss of the toner particle image or to impart a textured finish to the toner particle image. Different belts may be used for these different functions. Whether the belt fuser is integral to the reproduction apparatus or used as a post printing finishing device, the belt may periodically require changing, either due to damage or general wear, or because a different belt with a different surface finish is required. It is therefore desirable that the belt be capable of being replaced easily and quickly.